Just to add my spare $0.02, every good submission grappling school that I've every been to teaches the guard, side control & mount as positions from which to transition, finish or escape (depending which position you're in and what openings you're given) the engagement, rather than as an optimal place to stay and hang out.

Matter of fact, last night at the BJJ school I like to visit, the drill was "Iron Man", where you get five two-minute rounds with a fresh guy each time. The first round you both start from the knees, each successive round, the guy that stays in gets put in a worse position (side mount, full mount, etc) and needs to start and work from there. This gets repeated so that everybody gets to be the Iron Man, as well as one of the guys sent against him.

In my mind, this specific drill accomplishes a couple of things from a combatives perspective: 1) You learn how key positional advantage is and how sometimes the best you can do is 'survive' a tough one with determination and heart. 2) As you get progressively tired and faced with fresh partners, you have to keep your head and "feel" what's going on around you (especially in a small space with a lot of other people training - does wonders for 'zanshin') in order to escape, finish or transition.

Now, the above examples are for the purposes of illustrating how BJJ, in this context, trains the practitioner to develop desireable skills within its paradigm. Does aikido have its own methods for training its desired traits? Undoubtedly. The success of which seems to be a big subject of debate and one I'm not really interested in participating in other than to say that I think honest assessment of one's training methodology is a necessary phase for any practitioner.

It isn't a one-and-done-thing either, but a constant evaluation of a) Am I honestly meeting my goals for training? b) Am I honestly improving in accordance with those goals at a pace that is acceptable? c) Am I also meeting my teacher's expectations? d) Are my and my teacher's expectations in harmony?

Sometimes the answers will change, but that's because our perspective on things tends not to be static. If it is, that to me is a clear indicator that I'm no longer learning.